1. Technical Field
The present invention relates to liquid crystal panels and projection liquid crystal display apparatuses, and particularly to a liquid crystal panel including a resin light-shielding film and a projection liquid crystal display apparatus using the liquid crystal pane.
2. Related Art
A twisted nematic (TN) or electrically controlled birefringence (ECB) liquid crystal panel has pixel electrodes and a common electrode that are disposed on their respective substrates. On the other hand, a fringe field switching (FFS) or in-plane switching (IPS) liquid crystal panel has pixel electrodes and a common electrode that are disposed on the same substrate.
In the TN type, a chromium (Cr) light-shielding film is generally formed as a black matrix on the substrate having the common electrode. Since chromium has a high light reflectance, the light-shielding film may be made of a composite including a chromium layer and a low-reflectance chromium oxide layer. In the FFS type, the light-shielding film is formed of a resin on the substrate having no electrode. This is because a metal layer of the substrate opposing the pixel electrodes and the common electrode with the liquid crystal layer therebetween, or electrification causes an electric field generated from this opposing substrate to affect the electric field between the pixel electrodes and the common electrode, thereby degrading the display quality.
The above-mentioned chromium light-shielding film and resin light-shielding film are disclosed in Japanese Unexamined Patent Application Publication No. 9-258203.
Resins used for the light-shielding film have optical densities (OD) in the range of, for example, 3.0 to 4.0, and the OD values of resins are generally lower than those of chromium and chromium oxide. Chromium and chromium oxide can have OD values of, for example, 4.0 to 4.5. Therefore, the resin light-shielding film is liable to cause light leakage in comparison with the chromium light-shielding film. Light leakage tends to be conspicuous when a high-intensity backlight is used.
In general, organic resins have lower adhesion to glass, which is an inorganic material, than chromium and chromium oxide. Accordingly, the resin light-shielding film is liable to separate from the substrate. If the light-shielding film separates, moisture enters the liquid crystal panel through an edge of the panel to degrade the reliability.
If the resin light-shielding film is formed using a resist film, the above problems are liable to occur because of the low OD value and adhesion.